Automatic train control system for railroads having coded and noncoded track circuitterritory



Mar h 24, 1953 J D. HUGHSON AUTOMATIC TRAIN CONTROL SYSTEM FOR RAILROADS HAVING CODED AND NONCQDED TRACK CIRCUIT TERRITORY Filed 001:. 9, 1946 4 Sheets-Sheet l w k g 7 zVENT R. Y I

Hi5 ATTORNEY March 24, 1953 J D. HUGHSQN 2,632,844 AUTOMATIC TRAIN CONTROL SYSTEM FOR RAILROADS HAVING CODED AND NONCODED TRACK CIRCUIT TERRITORY Filed Oct. 9, 1946 4 Sheets$heet 2 FIG|.1B.

H is. ATTORNEY J D. HUGHSON March 24, 1953 2,632,844 AUTOMATIC TRAIN CONTROL SYSTEM FOR RAILROADS HAVING CODED AND uoncomzo TRACK cmcun TERRITORY Filed Oct. 9, 1945 4 Sheets-Sheet I5 cw m ru 3596 wuumn co m W zeELozv wudpco boom 100mm 33 m an. V T fl M44 A-+v zozouua i5 #5 I n U .m H avumvkuzuunq W 2. 65

March 24, 1953 J D; HUGHSON 2,632, AUTOMATIC TRAIN CONTROL SYSTEM FOR RAILROADSHAVING CODED AND NONCODED TRACK CIRCUIT TERRITORY Filed 001:. 9, 1946 4 Sheets-Sheet 4 $6 XU n n I n u L A q a n A i mm W l I n n u M I n u 96 M .n m..5w n M A p 0 n .T a0. A n v 0- mww mm A u n q I u r U nd a u u u q MHT a2 1 I l i fin mm i V v I 5 3 v2.1a; .0 I S 6 5m 2 .0 3: 3 Ha s C p ES H3 5 SQ Ere 59 5 E .Q 5 E 4 h 3 :2 u -u :15 wzou sLuw rpofitu o -u3u Hn:o:=w=ou E MA- oewuaw wco ELuwc c0300.:

His ATTORNEY Patented Mar. 24, 1953 2,632,844

UNITEDTSTATE'S PATENT OFFICE, i

' AUTOMATIC TRAIN CONTROL SYSTEM FOR. r I RAILROADS HAVING CODEDLjAND NON- r min TRACK CIRCUIT, TERRITORY J Donald HughsomRochester, assignor to i geiieral'ltailway Signal Compan Rochester,

" Application October 9, 1946, Serial No. ;702, 325

"c1ai 's;; (01. 246 6 3) t I "This invention. relates to automatic train controlasystems forrailroads, andmore particularly pertains to automatic traincontrol systems of the intermittent and continuous inductive types.

somewtrain control systems, an inertwayside-inductonis located at spaced intervals along thetrackwaysand is controlled in sucha way as to t-inductively affect train carried apparatus in accordance with traffic conditions. In other systems, train carried apparatus is governed in accordance with traffic conditions by reason of codedcurrents in'the rails of the trackway. This provides what is known as continuous inductive control; whereasthe spaced inductor organization above mentioned provides what is known as intermittent inductive control. j

In -some cases, a portion of a railroad will be provided with intermittent inductive train-control and an adjoining portion of the railroad will havelcontinuous inductive control applied thereto. vFor example, it sometimes occurs that a railroad will change from the intermittent inductive typeof train ,controlto the continuous typeisince the latter provides amore comprehensive system. During thistransition period there are some locomotives equipped for only intermittent inductive... control and others which are equipped with continuous inductive control. Also, there are portions-of the trackway which are providedwith only the. intermittent inductive control. Thus-it maybe said'to be an object of the present invention-to. provide, traincarried ape paratus which. is. efiectivefor operation in Y territo ry equipped for either intermittent inductive control or continuous inductive control, and which will also properly operate in territory equipped with .bo'th'kinds of control during a transition stage in which .a shift is being made from'one type to the other.

furtherobje'ct of the present-invention is to provide train carried apparatus which .willact to automatically shift between one, type of train controlland the other subject to certain acknowledgments on the part of the-.itrainmaninorderto assureltheiproperiandsafeloperation of the train.

' A f-urther. obj'ectiofthe invention is to provide train .carriedapparatus which {is responsive both to .intermittentinductive ,train control and to continuous. inductive train. control in .such a manner that thesame brakeapplying; apparatus maybe p 2 i utilized for both systems, although each system provides distinctive indications on the train. V 1; Other objects, purposes and characterisjc' features of the present invention will be in part obvious from the accompanyingdrawings, and part pointed out as the description of the inveni tion progresses. f In describing the invention in detail; reference will be :made to theaccompanyin'g drawings, in which like reference characters designate corre': sponding parts throughout the several viewsrand in which: Figs. 1A and 13, when placed end ,to end illustrate diagrammatically the wayside equipment for a system of train control embodying the pres-- ent invention; i

Fig. 2 illustrates diagrammaticallylthe train carried apparatus embodying the present inventionyand f Figs. 3A through 3G are diagrams indicating the different conditionsof acknowledgment required by a trainman as a train passes through the territory equipped with train control apparatus as provided in-accordance with the present invention. a i

For the purpose of simplifying the illustration and facilitating in the explanation, the various parts and circuits constituting the embodiment of the invention have-been shown diagrammatic-ally and certain conventional illustrationshave been employed,the drawings havingbeen made more with the purpose of making it easy to understand the principles and mode ofoperation, than with the idea of illustrating the specific construction and arrangement of parts that would be employed in practice. Thus, the various relays and their contacts are illustrated in aconventional manner,; and,symbols areused to indicate the connections to theterminals of batteries, orother sources of electric current, instead ot-sho-wingliall of the wiring connections to these terminals} The symbols (-ll -and are employed to indicate the positive and negative terminalsyrespectively' of suitable batteries, or other purcepr direct current; and the circuits with which .these s bo ls areused,"always have current flowing in the same direction. v. f

,jljhe, symbols (BX): and ,(CX) are employedto indicate connections to thejopposite terminals of alsuitable source-of alternatingcurrent suc a one hundred cycle alternating current supply which is usually employed in train control systems so as to avoid the possibility of false indications from stray commercial sixty cycle alternating current. On the other hand, these terminals may indicate a conventional sixty cycle commercial supply of alternating current provided the train carried apparatus is adapted to receive only the second harmonic of the wayside frequency as shown and described in my prior application, Ser. No. 685,575, filed July 23, 1946, now Pat. No. 2,503,671, dated April 11, 1950.

Wayside apparatus-For the purpose of explanation of the present invention, a stretch of track including track sections IT, 2T, 3T, 4T and BT, has been shown, although it should be understood that these track sections are assumed to be only a portion of the entire stretch equipped with train control facilities. The track sections IT and 2T are assumed to be in train control territory of the intermittent inductive type, as indicated in the diagram of Fig. 3A. Similarly, the sections 5T and BT (indicated in Fig. 3A) are assumed to be of the intermittent inductive type. Between these two sections of intermittent inductive wayside equipment, the two track sections 3T and AT are assumed to include both coded track circuit apparatus for continuous inductive train control and also the wayside track inductors for intermittent inductive train control. It is, of course, to be understood that instead of only the two track sections 3T and 4T, any number of track sections might be similarly equipped. This arrangement has been indicated in Fig. 3A to indicate the situation in which a railroad is changing from the intermittent inductive type of train control to continuous in ductive train control and at the same time providing coded track circuits for governing the wayside signals in place of line wire control.

Referring to Figs. 1A and IE, it will be noted that the wayside has been shown as provided with signals 2, 3, 4 and 5 as indicated by suitable symbols. These signals are capable of giving green, yellow and red indications designated by the letters G, Y and R, and are assumed to be of the color-light type. Their respective lamps designated by these letters G, Y and R are associated with each signal and are suitably controlled to give the proper indications.

In connection with the signal 2 of Fig. 1A, the signal lamps are governed by two line relays 2LR+ and 2LR.-. These relays are assumed to be of the biased polar type such as shown in the prior application of George E. Duffy, Jr., Ser. No. 542,203, filed June 26, 1944, now Patent No. 2,414,583, dated January 21, 1947. However, it should be understood that other types of line relays might be employed if so desired.

The track sections IT, 2T and ET are assumed to be of the direct current steadily energized type, each provided with a suitable track relay. In Fig. 1A it will be noted that the track relay 2TB, suitably governs the line circuit of the line relays 2LR+ and 2LR-. Also, since the line circuit for track section 2T adjoins the coded track circuit section 3T, it is controlled by the decoding apparatus at signal 3. However, when a line circuit section adjoins another line circuit section, the line circuits are associated with each other as shown for signal 2.

Also associated with the signal '2 is a wayside track inductor designated 2T1 which has a winding governed by the line relays 2LR+ and 2LR. A similar track inductor TI is provided at each of the signal locations with a suitable preceding numeral characteristic of that location, but at the signal locations where the signals are governed in accordance with the coded track circuit control, the wayside track inductors are governed by the distant decoding relays, such as relay 3D in Fig. 1A for the signal location 3. Each track section equipped with coded track circuit apparatus, such as section 6T, has code transmitting equipment including a track transformer 4TT with a secondary winding connected across the track rails in series with a rectifier unit 4B and with a primary winding supplied with coded track circuit alternating current energy in accordance with the particular code selected dependent upon the traffic conditions. When a coded track circuit section adjoins a line circuit controlled signal, such as signal 5, then the codes are selected by the associated line relays; but, when such coded track circuit section adjoins another coded track circuit section, then the codes are selected by the decoding apparatus adjacent the associated signal, such as at signal 4.

These half-cycles of alternating current applied to the track section 4T, for example, act upon a suitable polarized direct current relay 4TB to cause it to be picked up for each series of half-cycles constituting a code pulse. This operation of relay 4TB. in turn acts on the decoding transformer to control a home relay 4H to an energized position whenever a track circuit code of any selected rate of code pulses is received. The decoding transformer also supplies energy through suitable tuned circuits and a receiver unit to pick up a decoding relay 4D only when pulses of the high code rate, such as 180, are received. The various codes employed have been illustrated as supplied from suitable coders having contacts and |80C for providing codes of the 75'code rate and the code rate as desired. However, these rates are only illustrative, it being understood that different rates may be employed as desired.

At the location of signal 4, the relay 4H is shown as controlling the code transmitting relay 3CP which is employed to govern the application of code pulses of alternating current to the track transformer 3TT. It is, of course, understood that the application of code pulses to the track circuits may be effected in different ways. However, for the purpose of this disclosure it may be assumed that one hundred cycle train control alternating current is connected to the terminals designated (BX) and (CX), and this supply provides half-cycles to the track circuit which is effective both to actuate the track relays at the entering ends of the sections, and to also provide an inductive control for the continuous inductive train carried apparatus illustrated in Fig. 2.

Car carried apparatus.-With reference to Fig. 2, a typical organization of car carried apparatus is illustrated. This apparatus includes continuous inductive receivers and also an intermittent inductive receiver, as indicated by corresponding legends on the drawings. The continuous inductive receivers are so located on the locomotive in front of the pilot wheels as to be responsive to the code pulses of current in the track rails; whereas, the intermittent inductive receiver is preferably located on the side of the locomotive so as to properly cooperate With the wayside track inductors located at intervals along the trackway.

The continuous inductive receivers act through suitable tuned circuits upon the input to a suit ablelamplifier .whichoprovidesiat sufficient, "level of T; energy output for! operating a. master relay MR for each codelpulserceived; Thisoperae tion' of theomaster relay accordance with the difiereut code rates. actsithrough aodecodingi transformer to cause the code responsive relay QR to be steadily picked up for-any of the code rates employed. The 'inaster reliay MR also supplies pulse energy to a tuned circuit and trans-..

code rateythua' the relay HCR'will be steadily picked "up nly when the rha'ster relay M3 is cpleratedat'this 180 code rate. f 5 "The reception of mo ow'o de rate," such as a 75' rate, causes the code responsive relay OR to steadily maintainits 'front contact'liii closed to complete a circuit to back contact 31 to energize the relay YR; whereas, if the 18(1 code rate is received, therel'ay HCR is also-energized so as to closev front contact 31, and energize the relay GPO instead of. the relay YR. While code pulses are being continuously received by the continuous inductive ,portion of; the system, a relay Si is deenergized closing back contact 38, sothat if the relay GR is picked up to close front contact 3.9. by reason of the reception of the 180 code, rate, then the green indicator G of the continuous inductive. cab signal C10 is illuminated. On the other hand, if only a '75 code rate; isbeingreceived, thentherelay YR is picked up and the yellow indicator lamp Y of the cab signal C10 is energized through the front contact 42. However, if, no code pulses are being received both relays GR and YB are deenergized and vthered indicator B, of the cab signal CIC becomes illuminated; unless an acknowledgment has beenmadeto energize the relay SI as will be later described 1 s 'lin addition to thecontinuous inductive control cabsignals indicated withinthe dotted rectangle CIC, an intermittent inductive control indicator is shown within, the dotted rectangle 110. This indicator may be of any suitable color other than those used for the cab signals such as-white, and for c qnv eniencethis lamp has been designated W.

Associated with, the intermittent inductive re ceiver is suitable apparatus including relays R l, R2 and Bit-tor responding to'the'tcontrolreceived from" the, wayside through the medium of; the wayside track inductors These relays Bl ,R2 and R3. are preferably specially constructed with balanced armatures. and'conta'cts' for use in train control operation; i'For-this'reasonthe contacts foreach of'these relays are'sh'own as pivoted at midpointslocated at one side of the relay. That portion of each "contact" directly adjacent the ,relaywinding is shown as biased away from the relay'by a suitable spring which moves allpor tions-of the contacts, around the pivot"point; When a' contact is inits biased position the relay maybe considered as non-operatedor released, but when the relay winding is energized and the contacts 'are moved around their pivot. points against normal biasthe relays'may then saidlto "iThese'relaysjRL'RZ and "R3 act'to govern an electropneumatic valve EPV; Morejsp'ecifically, no; "train passes arestrictivdsignal indication,

thetime of passing thewayside inductor. Simi-j, w larly, while under continuousinductive control,

achange from a green indication to a yellowindication dueto a change from the high code rate.

to the low code rateina track section also requires an acknowledgment by the actuation of the button; ACK within a limited time. In both-cases,

edging buttonlimitsiithe length ofltime thatvan,

acknowledgment mayfexist ,tojia .specified time such as for example zolsecondsj This time delay contact 3 l is for the purpose of preventing a train-r '1' man from continuously holding the "acknowledg-' ment button ACK in an. operated .position, .because under such a circumstance the features .of acknowledgment would be obviated. Thus,..if too long an acknowledgment is made, this contact 3i opens and deenergizes theielectroepneumatic valve EPV causing the train to be automatically stopped byabrake application. 1

A suitable acknowledgingrelay AQKR' and two. stick repeater relays SI ,and SZ -are provided ito-l gether with two slow release valve controlling relays VRI and VH2. ,These relays provide the control for the inter-relationbetween the two system components which will be. described in greater detail hereinafter.

A whistle valve CWV is normally energized and is associated with the continuous inductive control in such a way that a ,changein indication from green to yellow causes this whistle valve to be deenergized effecting the sounding of a whistle which continues until a suitable acknowledgment has been made. On the other hand, a whistle valve IWV is provided for the intermittent portion of the system and is normally deenergized but causes its whistle to sound whenever it is energized which occurs during an acknowledgment for the intermittent component of the system. V

A speed governor is'associatedwith the locomotive in such a way that it is operated in accordance with the speed of the locomotive and determined low speede Thus; should the train attain a speed above the maximum allowable speed limit, the el'ectro pneumatic valve EBVis deenergized' causing a brake application to be automatically made. Thi$ potentialpossibility makes it desirable for the trainman to at all times maintain the-opei-ation-ofhis train "at 'a speed in conformance with the selected speed limit. If for any reason, an automatic brake application is made, due to failure to properly acknowledge a signal indication; it-is necessary in order to restore the system to an operative condition releasing the brakes of the trainto reduce the speed of the-trainto-a value below the low speed at which the resetcentact of the governor is closed; and his also necessary to actuate the acknowledging button ACK. This reset speed may befloifany predetermined low speed value, or maybe suchas to require the tram to actuallycometo a stop.

If the train exceeds a predetermined maximum speed, the maximum speed contact on the governor opens and releases the electro-pneumatic valve EPV causing a brake application. When the train reduces its speed to a proper value, the electro-pneumatic valve EPV is reenergized, rendering the brakes of the train subject to the manual control of the engineer.

A ballast lamp BL is provided for the purpose of supplying a substantially constant current to the primary winding P of the intermittent inductive receiver regardless of slight variations in the supply potential for the system. A check lamp CKL is provided to be illuminated whenever the train is brought to a predetermined minimum speed, or when the trainman acknowledges a change in signalling conditions.

It is believed that further characteristic features of the system embodying the present invention will be best understood by further description being set forth from the standpoint of typical operations and conditions involving typical operations.

Operation Since the typical trackway circuits of Figs. 1A and 1B show an intermittent inductive territory on each side of a continuous inductive territory, it is perhaps desirable to consider the conditions of the train carried apparatus for intermittent inductive control before considering the conditions of the apparatus for continuous inductive control. However, it should be noted that the so-called continuous inductive territory also includes wayside inductors for intermittent control so that if a train is equipped only with intermittent inductive car carried apparatus, it can properly proceed through the entire stretch. In considering the normal conditions of the intermittent inductive control apparatus on the train as shown in Fig. 2, it must be appreciated that the master relay MR is not operating and that the relays CR and HCR are both continuously dropped away. Thus, the car carried apparatus for intermittent control is properly conditioned for proceeding along the trackway only providing the acknowledging button ACK has been actuated prior to the initiation of train movement. However, since the functioning in response to such actuation of the acknowledging button ACE is the same as when the train passes from a continuous inductive territory into a territory not equipped in this manner, the description of such acknowledgment will be set forth under the consideration of that type of condition instead of at this time. For the present, it is believed sufficient to point out the normal conditions of the car carried apparatus assuming that it is in condition for proceeding through an intermittent inductive territory.

Under normal conditions, the relay R3 is energized by a circuit closed from and including contact 23 of relay R2 in an operated position, contact 30 of relay R3 in an operated position, windings of relay R3, ballast lamp BL, primary winding P of the intermittent inductive receiver, to The current which flows through this circuit for relay R3 is maintained substantially constant due to the characteristics of the ballast lamp BL.

The relay RI is energized by a circuit in multiple with the relay R3 and includes contact 33 of relay R3 in an operated position, contact 32 of relay RI in an operated position, secondary winding S of the intermittent inductive receiver, windings of relay RI, to the left-hand terminal of relay R3. It is noted that the current flows in the direction of the circuit just traced as indicated by the arrow. The current which flows in this circuit for relay RI is of a value relatively small compared to the value of current flowing through the relay R3 for reasons which will be presently explained.

With both of the relays RI and R3 in operated positions, a circuit is closed for the relay R2 from and including contact 29 in an operated position, contacts 30 and 33 of relay R3 in operated positions, contact 34 of relay RI in an operated position, windings of relay R2, to

With these three relays RI, R2 and R3 all in operated positions, the electro-pneumatic valve EPV is maintained energized by a circuit closed from and including contact 29 of relay R2 in an operated position, contact 30 of relay R3 in an operated position, front contact 28 of relay VH2, non-operated time delay contact 3! of the acknowledging button ACK, maximum speed contact on speed governor, windings of EPV, to This energization of the electro-pneumatic valve EPV maintains the brakes of the train released so that it can proceed over the trackway.

The above circuit just traced for the electropneumatic valve EPV includes front contact 28 of relay VR2, which relay is energized through a front contact 27 of relay VRI. This relay VRI is in turn energized by reason of a circuit closed from and including front contact 25 of relay SI, front contact 26 of relay VR2, windings of relay VRI, to This circuit is in effect a repeated stick circuit for the relay VRI which is maintained energized by the energization of relay Si under the conditions being considered. Relay 8-! is energized by a circuit closed from and including front contact 24 of relay S2, back contact 22 of relay CR, windings of relay sl, to This circuit is in effect a repeated stick circuit for the relay SI by reason of the continued energization of relay S2 through front contact 23 of relay Si. Thus, it will be seen that all four relays SI, S2, VRI and VR2 are now energized by reason of their initial energization under proper conditions which will be explained hereinafter.

The normally energized whistle valve CWV is maintained energized by the supply of energy through front contact 25 of relay SI. Also, an indication is given to the trainman that the intermittent inductive train control is in effect by reason of the illumination of the lamp W of the indicator IIC, since the lamp W receives energy through front contact 38 of the relay SI.

Passage of train-Referring to Figs. 1A and 1B, let us assume that an eastbound train is travelling through the stretch from left to right. The presence of a train in the track section 2T causes the track relay 2TR to open its front contact l5 deenergizing the line relays 213-}- and 2LR-. This causes the red lamp R of signal 2 to be energized by reason of a circuit including back contacts 16 and ll of these line relays to glve a stop indication. Under these conditions, the track inductor 2T1 is open circuited by reason of the opening of front contact 18 of line relay 2LR+. In this way, any train which might otherwise inadvertently pass the stop signal 2 W111 have an automatic brake application performed by the intermittent inductive train control unless the trainman properly acknowledges such danger signal as it passes the track inductor 2TI.

"indication,

'tial'which picks up the line relay 2LR+ and lcauses the green indicator lamp G-of signal 2 "to: be. energized thr'oughba'ck contact83 and W front, contact 8 5 With the line relays in this condition, the tr'ack inductor 2T1 has its winding 6;,

by reason of the closure of back contacts 19 and 80 which will cause the line relay lLR (not shown) to be energized for causing that signal to display a caution or yellow indication.

Assumin that the train moves from the track section 2T into the track section 3T, such train would, of course; receive a green indication'at 10 signal 3' sincethere is'no train assumed to'be in advance of it. Also, the track inductor 3T1 would be short circuited by reason of the closed condition of front contact 8!- of the distant relay 3D since it is energized by'reason of thereception of a 180 code as previously-explained. The entrance of the train into the track section 3T causes the track relay STR/to cease opera tion and hence results in the release of both relays 3H and 3D. This causes the red lamp R 0 of signal 3 to be energized and-opens the circuit for the trackway inductor 3TI to protect the rear of the train. The release of the relay 3H shifts the polarity on the linecircuit extending tosignal 2vby closing back contact 32.

Since theitrain'is assumed to be out of the section ET, the track relay 2TR is energized closing front contact 15 'so that the negative energi'z'ation 'of the line circuit causes the response of" the linerelay 2LR-. The opening of back 39 contact 'l'ldeenergizesthe red lampR while the closing yofifront contact 83 energizes the yellow lamp fY through a circuit also includingback contacts 84.01 line relay",2LR,+. The opening of backcontacttias' well as the opened condition of frontcontact l8causes the trackway inductor ,2TI to be deenergized to cause the intermittent train control .of; any train'passing such signal to automatically makebrake application if the traininandoes notprope'rly acknowledge such 40 caution signal; The closed; condition of front contact 86 of relay 2LR and the closed con- 'dition of back contact 8"! applies positive energy .to the line circuit extending tosignal I- (not shown) so that such signal I will give a 'clear When the train moves from the track section 3T intothe track section iT, the relays fiH-and 4D are similarly caused to be 'deenergized. and theopening of front contact 88 of relay 413 causes mthetrack inductor tTI to be deenergizedwhil'e the closure of back contact 89 causes a75 code tr be. appliedto the track sectiontT Such code causes the signal 3 to" give a -caution indicationf by energization of the relay 3H closing 5 front contact 90 toenergize the lainp Y through ,back contact 9|. The energization of-tlier'elay 3Hv closes frontcontact 82150 energize the line circuit extending to signal 2 with positive poten- .releasesFtheline relay 2LR. 1 This, of course,

circuit closed through" front contact la andib'ack contact, 85.

I From the above description, itwill beseenthat asthe. train passes through the successive to cause the" signal immediately'in the rear of the train to give a red or danger in cation while second'sigrial -fii the iear-is"-cafisd"tdgive a yellow or caution indication. In each case the 75 ceiver passes over theiriductor; Sinc'ethe" 1- third signal inthe rear is caused to give green or clear indication. At all signal locations that give a caution or danger indication, the track way inductors are open circuited to cause an effect upon the intermittent train control in such a way as to efiect an automatic brake application. On the other hand, at the signal locations which display green or clear,,the trackway inductors are short circuited which causes such in- .duotors to. have no effect on the intermittent inductive car carried apparatus.

It will also be noted that the presence of a train in a coded track circuit section causes the track relayatthe. entrance of that section to cease operation so as to render such section dead insofar-as the-presence of code pulses are concerned. Tl' is condition causes the signal at the entrance to such section to display a stop indication, and such absence of code in a section would, of course, give a corresponding indication-for the continuous inductive train control apparatus on a train entering that section. In the section next to the rear of an occupied section, a 75 or low code rate is applied which causes a caution indication to be displayed by the'signal rat its entrance end and---willcorrespondingly affect the "continuous inductive car carriedappa ratus of a train enteringthat section togive a yellow indication" on" 'thetraini" In tlie second section to the rear of" an occupied track section,

the traincai'ried apparatus.

Intermittent inductive controll -"Asabovemen- :tione'd; the passage of a"traimpastatrack in" "ductorTI has no effect on the train carried ap paratusif the w ding of suchi riductor is short "circuited? butif the winding of the'track "ductor is not short circuited, th'enthe "iron of the track inductor acts *tocomplete amagi etie path between the opposite poles of the car-carried intermittent inductivereceivenas such remaryjfwin' dingl? of the receiver is stadily'pnefgized with direct current, this movement of the receiver" over th' trackway inductor caus a see is etering: esnr e f jn ondary winding S. jjIhis surge jcauses sections,;the trackway'circuits, either of the line 70 wire typev or of the coded track circuit type act relay R3, and the positive wave of the induced cycle has no effect on the relay R3 even though it is in the opposite direction to its normal energization since this induced current cannot flow through the relay R3 because contact 32 has been opened by the negative portion.

The release of the relay R! causes the opening of contact 34 releasing relay R2, which in turn opens the contact 29 to release the relay R3. If this occurs without the actuation of the acknowledging button ACK, then it is apparent that energy is removed from the electro-pneumatic valve EPV by reason of the opening of contacts 29 and 30 so that an automatic brake application is made to the train, and these relays cannot be restored to their normal conditions until the train is reduced to the low speed at which the reset contact on the speed governor is closed.

When the low speed contact is closed and the acknowledging button ACK is actuated, a circuit is closed from (-1-), through the intermittent whistle valve IWV, acknowledging button contact 45 in operated position, front contact 59 of relay S2, acknowledging contact 41 in an operated position, low speed reset contact on speed governor, through the relay R3 and primary winding P, to This energizes the relay R3 to close its contact 33 to cause current flow through restoring contact 35 of relay R2, operated contact .46 of acknowledging contactor ACK in an operated position, relay RI ballast lamp BL, primary winding P, to This energization of the relay R! causes the closure of its contacts 32 and 34 which causes energy to flow from the right-hand terminal of relay R3 through contacts 33 and 34 to energize the relay R2, as soon as contact 29 of relay R2, is closed, the acknowledging contactor ACK can be released and the relays Ri, R2 and R3 will remain in their energized positions as shown. The application of energy to the right-hand terminal of relay R3 also causes energy to flow through front contact 28 of relay VR2, time delay contact 3!, maximum speed contact or speed governor, windings of electro-pneumatic valveEPV, to This energization of the electro-pneumatic valve EPV, of course, restores the system to normal conditions so that the brakes can be released and the train can proceed.

However, it should be noted that the train may pass a trackway inductor TI which is open circuited Without the application of the brakes if the trainman actuates the acknowledging button ACK during the passage of the train over such inductor. This closes the contact 45 so that energy is maintained on the relay R3 as supplied through the whistle valve IWV and also maintains energy applied to the electro-pneumatic valve EPV. Although the induced current in the secondary winding S of the receiver causes the release of relay RI followed by the release of relay R2, these relays are immediately restored in the same order since energy is supplied through contact 33. The restoration of these relays occurs immediately so that the acknowledging button ACK can be released before the time delay contact 3| has had suificient time in which to open. Each time theacknowledging button ACK is operated, under the above circumstances, the contact 41 is closed and effects the illumination of the check lamp CKL but the whistle IWV is not energized until the relay R2 is deenergized upon the passage of the train over the inert inductor. As soon as the relay R2 is again restored, the energy applied through contact 29 to the circuit removes the potential drop across the whistle valve IWV so that it is deenergi'zed and the whistle becomes silent. In this way, the train is able to pass through the intermittent inductive territory and pass restrictive signals as required by the circumstances without automatic brake applications so long as the trainman acknowledges such restrictive signal indications. Such acknowledgement indicates that the trainman is alert and is assuming the responsibility of properly governing the trains speed in accordance with the conditions of traffic all of which is well understood in the art of train control.

Continuous inductive controZ.When the train enters the first track section of continuous inductive control, such track section, of course, has coded pulses of half cycles of alternating current applied thereto. The half cycles of each code pulse are efiective to produce an electro-magnetic effect in the continuous inductive receivers, which produces electric potentials that are amplified to cause' the actuation of the master relay MR. Any of the selected code rates, causes the code responsive relay CR to be picked up which opens back contact 22. This releases the relay Si, which in turn releases the relay S2. During the dropping away of the relay Si, which is slightly slow'release, the acknowledging relay ACKR is also released, but the relay CR being picked up closes its front contact 36 and assuming that the code is of the high code rate, the relay HCR is also picked up permitting the energization of the relay GR through front contact 3?. This not only causes the green indicator G of the cab signal CIC to be illuminated, but also closes front contact 44 which completes a circuit for the normally energized whistle valve CWV from (-1-), through a circuit including front contact 5i of relay VR2, front contact 44 of relay GR, back contact l! of relay ACKR, back contact 25 of relay SI, windings of whistle valve CWV, to This whistle valve CWV must be continuously energized in order to keep the whistle from sounding. It should also be noted that energy from the heel of contact 25, is also supplied through front contact 26 of relay VR2 to the windings of relay VRI to maintain it energized. This relay VRI, of course, in turn maintains relay VR2 energized through its front contact 21. In this way the entrance of the train into continuous inductive territory causes the relays VRI and VR2 to be maintained energized even though the acknowledging relay ACKR is released together with the relays S! and S2. Under these conditions the train carried apparatus is entirely dependent upon the continued reception of code pulses. If the train passes a signal indicating caution, so as to enter a track section having only the low code rate, it will be apparent that the relay HCR becomes deenergized and in turn the relay GR. Of course, the relay YR is picked up closing front contact 42 to cause the yellow indicator Y of the cab signal 010 to be illuminated instead of the lamp G. The front contact 43 of the relay YR is closed. However, the opening of front contact M of relay GR causes the deenergization of the whistle valve CWV which results in the sounding of the whistle. At the same time energy is removed from the .relay VRI but this relay is a slow release relay so that if the trainman acknowledges reception of a more restrictive signal indication within a limited time, the relay VRI is maintained energized 1andt the Whistle valve CWV has energy restored More specifically, let us assume that the train entersthe more restrictive section,and that the release of the relay GR causes the whistle to sound; The trainman immediately actuates the button ACKwhich applies energyto the relay ACKR through its upper winding by an'obvious circuit previously pointed out. As soon as relay ACKR picks up, it is maintained stuck up by the supply or energy through; the contacts 43 and applied to its lowerwinding. Since the relay CR. is picked up under such circumstances,

I it is apparent that back contact 22 is opened so thatthe relay SI is not energized This means that energyisthen supplied from; through front contact 43 of relay YR front contact of'relay ACKR, front contact of relay ACKR, back contact 25 of relay-Si, to the; whistle valve CWV, to Also, energy from the'heel ofcontact' 25 isisupplied through front contact 26"of're1ay VRZ to the relay VRI so that it is either maintained'picked up, or is restored; if such restoring circuit is closed prior to the release "of' theslow'acting relay VH2. Thus; the whistle is silenced and the relays VR! and VRZ are caused to be maintained picked up providing the trainman actuates the button ACK within' the release'times of these relays.

On the other hand, if the trainman failed-to actuate the button ACK, or failed to actuate'it der the above conditions'withthe'train at stop or at least sufliciently slow in its speed to close the reset contact, permits the-picking up of the relays ACKR S-i and S2. The closure of "the front contact of relay Sljof course, causes application of energy to the relay VRI, so" that the buttonAC'K maybe released} "This similarly will permit the train to proceed;

In this connection, it" should be notedthat when-the train leaves the continuous inductive 'tinuous inductive territory, it is also noted that sufficiently soon, the relay VH2 would releaseopening contact 26 50 that the relay-VRl would not be energized. This would also open front contact 28 and cause the removal of energy fromth'e electro-pneumatic valve EPV resulting in an automatic brake application. It is also noted that the releaseof the relay VRZ opens front contact 2| so that a late actuation of the acknowledging'button ACK cannot pick up the acknowledging relay ACKR. Thus, the whistle valve CWV cannot be reenergized even though the relay YR is picked up. Inthis way, the

continuous inductive train control portion of the system causes the automatic brake application to be made. However, the release of the relay VR2 closes back contact 5i, so that regardless of the passage of a train under such circumstances over an inert track inductor TI, such actiondoes not release the relay R3. In other words, even under such circumstances the continuous inductive control is in effect and the intermittent inductive control is maintained 1n its normal condition.

Inorder to restore the system under such This. permits energy to flow from (-1-) through a circuit, including back contact 5! of relay VR2, reset contact on speed governor, operated contact 41 of acknowledging button ACK, back contact5ll or relay S2, windings of relay VRI, to

(-2 As soon as the relay VBI is energized, it .reenergizes'relay VRZ so thatthe actuation of the acknowledging button ACK in, closing its contact 20 can, cause the picking up of the acknowledging relay ACKR; Thus, if the train 'is in a caution block where the relay YR is picked up, the) relay ACKR is stuck up and energy is supplied through back contact 25 to the whistle valve CWV and the relayVRl as previously explained. This permits the release of the acknowledging button ACK andthe restoration of the system to normal so that thetrain can then proceed. Ifthe train is in an occupied-block sothat the relay CR- is -not pickedum-then'the v i actuation of the acknowledging button ACK unthis territory includes track inductors TI which is for.use by those trains which haveequipments not yet changed over to the type shown in Fig; 2. Thus, each time a train equipped as'in Fig; 2

passes a'caution signal in the continuous inductive territory, the trackway'inductor isop'en "train enters the caution coded trackfsectidn.

But' in accordance with 'the'presentinvention, this is not necessary since during the passage of the train through continuous inductive territory the relays SI and S2 aredeenrgized. The closure of backcontacts" 48 and 49 act upon the intermittent inductive train control the same'as if the trainman' actually acknowledged by oper ation of the button ACKL In other Wordsene'rg'y is supplied through the whistle valve IWV at anytime that the passage or h inert conductor causes the release of the relays RI andRZ, while the closure of back cont acti49 permits the restoration of the relays RI and R2 the same as if acknowledgment had been made. In this way, it is unnecessary for the trainman to acknowledge the trackway inductorsin passing through continuous inductive territory.

The various conditions ofacknowledgment are indicated in the diagrams ofFigs-BB through 3G. In these diagrams, a trainA is shown in different sections'of the territory diagrammatically shown 'in Fig. 3A'and illustrated in greater detail in Figs. 1A and 1B. A' train Bis shown following the train A, and a suitable legend is-shown at each point at which an acknowledgment would be necessary by the train B ifit proceeded to approach the train A in the position shown for its diagram' For example, in Fig. 3B, the train A is shown as occupying section 2T, and the train 3 is shown as occupying the section lT. If the train Bpasses the wayside inductor at the signal 2 location, then the train- B would have to acknowledge the inductor which is indicated by the legend ACK IND.

Similarly in Fig. 3C, with the train A in the track section 3T, the train B would have to acknowledge the inductors at signal locations 2 and 3 if the train proceeded to approach the other.

signal 3 and would also have to acknowledge the cab signal at the signal 4.

With this explanation it isbelieved that the remaining diagrams 3E and SF will be readily understood.

In Fig. 3G, it is noted that the train A is not shown, but the train B must acknowledge the cab signal indication, as it passes the signal location 5. This is because the train is leaving the continuous inductive territory, and the trainman must acknowledge such fact as previously explained so as to avoid an automatic brake application and so as to condition the system for operation in accordance with the intermittent inductive control. This acknowledgment conditions the train carried apparatus as shown in Fig.

-2 so that it may proceed to operate through the intermittent inductive territory as previously described.

As above pointed out, the system organized in this manner permits the train carried apparatus of Fig. 2 to properly govern a train both in intermittent inductive territory and in continuous inductive territory, and is exceptionally suitable in the case where there is a changeover taking place from intermittent inductive to continuous inductive control. In such a case, the wayside inductors are maintained along the trackway both in the intermittent inductive territory and in the continuous inductive territory for the benefit of those trains which are equipped only for intermittent control. However, in accordance with the present invention, the train carried apparatus of Fig. 2 does not require acknowledgment of the wayside inductors while the train is passing through'the continuous inductive territory. Also, the leaving of the continuous inductive territory requires a suitable acknowledgment which conditions the car carried apparatus for the intermittent control which it will receive through the intermittent inductive territory. The car carried apparatus is also so organized as to permit each type of control to function in the same manner as it would function if it were used alone. For example, the whistle valves are controlled in the same way to give the same indications, and similarly the cab signals, check lamps, speed contacts and the like give the same type of control as would be effective if the two types of systems were not combined in a composite organization.

In the above consideration of the invention, it is assumed that a railroad is in the process of changeover from. one type of train control to an- However, the present invention embodied in the train carried apparatus of Fig. 2 is-just as adaptable for operation over a railroad having a portion provided with intermittent inductive wayside equipment and another portion provided with continuous inductive wayside equipment only. In

such a case, it is highly desirable to provide the automatic changeover features of the present invention. For example, if there were no automatic changeover from the intermittent inductive control to the continuous inductive control, and such changeover were accomplished by a manual act, such as the movement of a hand lever, it might happen that the trainman would forget to perform such act. The continuous inductive train control territory might be in a condition because of traffic requiring a danger cab signal, but since the trainman failed to perform the manual act the train proceeds the same as if it were in the intermittent inductive train control territory but with no inert track inductor to cause a brake application when the train enters the occupied track section. In other words, the automatic changeover provided by the present invention avoids the possibility of this dangerous condition due to the trainmans inadvertently forgetting to perform a manual act. Obviously, a similar condition is not present in going from continuous train control territory to intermittent train control territory, since the entrance of a train into a track section not provided with train control code pulses is the same as entering an occupied block and causes appropriate action of the continuous inductive train control portion of the system. 7

Having described a train control system as one specific embodiment of the present invention, it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations and alterations may be applied to the specific form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention.

What I claim is:

1. In a train control and cab signal system for railroads, a stretch of trackway having inductive devices located at intervals and controlled in accordance with trafiic conditions, a first receiving means including electrical circuit elements located on a train and cooperating with said inductive devices located at intervals along the trackway for at times being rendered active to cause an automatic brake application to the train unless otherwise acted upon at those times, an acknowledging contactor on the train, means rendered effective by the manual actuation of said acknowledging contactor for acting upon said first receiving means to prevent an automatic brake application when the train passes over a wayside inductive device that would otherwise cause said first receiving means to cause an automatic brake application, an adjoining stretch of trackway having successive sections supplied with different coded trackway currents and also having inductive devices located at the entrance to each section controlled in accordance with traffic conditions, a second receiving means including electrical circuit elements located on the train and controlled by currents in the trackway to automatically display different indications in accordance with the difierent coded trackway currents, and means governed by said second receiving means when it is responding to coded trackway currents for automatically acting to prevent an automatic brake application by said first receiving means when passing over an inductive device along the trackway that would otherwise cause such an automatic brake application.

2. In a train control and cab signal system for railroads, a stretch of track divided into a plurality of track sections, a trackway inductor located at the leaving end of each section and controlled in accordance with traflic in the sections in advance, coded track circuit apparatus associated with certain of said sections for transmitting different coded currents through the rails of those sections in accordance with trafiic conditions in advance, a first receiving means including electrical circuit elements located on a train and cooperating with said trackway inductors located at intervals along the trackway for at times being rendered active to cause an automatic brake application to the train unless otherwise' actd upon at those times, an acknowle ging-contactor on thetrain effective upon 'jnianualactuation for' preventing an automatic trake application bysa-i'd receiving means,

a second receiving means including electrical circuit elements 'located on the train and controlled by said difierentcoded currents in the ils to automatically-display di'fierent indicais one inaccordancewith the different codes, means governed -by-said second receiving means foi -causihg anautomaticbrake application upon enteringany section having no distinctive code currents its-track rails unless said acknowledging contactorisoperated-within a limited time, and circuit means for rendering said first receiving means inefiective when said second receiving means is controlled by coded currents in the rails of a section, said circuit means acting until a manual actuation of said acknowledging contactor occurs following the entrance of the train into a track section having no coded currents in the rails.

3. In a train control and cab signaling system for railroads, a stretch of trackwayhaving inductors located at intervals and controlled in accordance with traflic conditions, an adjoining stretch of trackway having successive sections supplied with distinctive trackway currents and also having inductors located in advance to the entrance to each section controlled in accordance with trafiic conditions in that section, a first receiving means on a train cooperating with said inductors located at intervals along the trackway for being rendered effective to cause an automatic brake application to the train when it passes an inductor which is in a particular condition unless said receiving means is otherwise acted upon, an acknowledging contactor on the train for operating a plurality of contacts in response to its manual actuation, circuit means including one of said contacts of said acknowledging contactor effective, when said contactor is manually actuated, for acting upon said first receiving means to prevent an automatic brake application when the train passes over a wayside inductor which is in said particular condition, a second receiving means on the train controlled by currents in the trackway to automatically display different indications in accordance with the distinctiveness of the trackway currents, said second receiving means also effecting an automatic brake application to the train upon entering any section having no dis- 7 tinctive currents in the track rails of that section unless otherwise acted upon within a limited time, a stick relay means having a pick up circuit including a contact of said acknowledging contactor and having a stick circuit closed independently of said contact of said acknowledging contactor, circuit means controlled by said second receiving means for opening the pick up and stick circuits of said stick relay means'whenever the train enters a track section having distinctive currents in its track rails, circuit means having a contact closed by said stick relay means when deenergized for rendering said first receiving means ineffective the same as if said acknowledging contactor is actuated, whereby a train traveling in said adjoining stretch is not subject to'control by said first receiving means, and circuit means including another of the contacts of said acknowledging contactor, effective when said contactor is manually actuated, for acting upon said second receiving means to pree vent an automatic brake application when the ans-1passesmtaaeaek setionfiavifig is distii'ictiy'e currents in its rails.

v 4. In a. trainfc'ontrol and car-signa ling, system for V railroads having a strata or trackway equip ed for intermittent and/o ccnti'n'ucus inductive train control, train carried apparatus comprising an intermittent inductive receiving means including electrical circuit elements for cooperating with the wayside inductors located at intervals along the trackway to be operated thereby in response to a distinctive condition, continuous receiving means including electrical circuit elements responsive to coded currents in the rails of the trackway, brake applying apparatus rendered active to stop the train in'response to the operation of said intermittent receiving means and also in response to the cessation of the operation of said continuous inductive receiving means by trackway coded currents for longer than a predetermined time, two forestalling relays, circuit means acting to prevent operation of said brake applying apparatus when either or both of said forestalling relays is picked up, an acknowledging contactor, pick-up circuits for said forestalling relays closable upon actuation of said acknowledging contactor, said pickup circuit for one of said forestalling relays being closable only if said continuous inductive means is not receiving a code, a stick circuit for said one of said forestalling relays closed only if said continuous inductive receiving means is not receiving a code, a stick circuit for the other of said forestalling relays closed only if said continuous inductive receiving means is receiving a code, and circuit means. acting to prevent operation of said intermittent inductive receiving means when said one forestalling relay is deenergized.

5. In a train control and cab signalling system for railroads having a stretch of trackway with wayside inductors located at the exit ends of successive track sections and distinctively controlled in accordance with traffic conditions and a portion of said stretch also equipped to impress coded currents on the track sections of that portion in accordance with trafiic conditions, train carried apparatus comprising an intermittent inductive receiving means including electrical circuit elements for cooperating with said wayside inductors to be operated thereby when an inductor is in a distinctive condition for one particular trafilc condition, continuous inductive receiving means including electrical circuit elements responsive to the coded currents in the sections of said trackway, brake applying apmeans effective to forestall a brake application.

when operated during the passage of a train over a wayside inductor and also when operated within said limited time following the cessation of said continuous inductive receiving means to respond to coded currents, and circuit means including a stick relay rendered effective in response to the manual operation of said acknowledging means when said continuous in- 19 ductive receiving means is unresponsive to coded currents for permitting the operation of said intermittent inductive receiving means, said circuit means being rendered inefifective when said continuous inductive receiving means again responds to coded currents in the track rails.

.i DONALD HUGHSON.

REFERENCES CITED The following references are of record in the file of this patent:

Number 20 UNITED STATES PATENTS Name Date Lewis July 25, 1922 Lewis et a1. Feb. 12, 1924 Preston Jan. 14, 1930 Loughridge Sept. 9, 1930 Rudolph et a1 Apr. 26, 1932 Baker June 21, 1932 Broadbent Feb. 21, 1933 Nicholson May 16, 1933 Allison May 30, 1939 Smith Feb. 13, 1940 Nicholson et a1. Oct. 15, 1940 Smith Feb. 25, 1941 

